Introduction to the Feeding of the Five Thousand
“And when even had come His disciples came to Him,” that is, at the consummation of the age in regard to which we may fitly say what is found in the Epistle of John, “It is the last hour.” They, not yet understanding what the Word was about to do, say to Him, “The place is desert,” seeing the desert condition of the masses in respect of God and the Law and the Word; but they say to Him, “The time is past,” as if the fitting season of the law and prophets had passed.
Perhaps they spoke this saying, in reference to the word of Jesus, that because of the beheading of John both the law and the prophets who were until John had ceased. “The time is past,” therefore they say, and no food is at hand, because the season of it is no longer present, that those who have followed You in the desert may serve the law and the prophets. And, further, the disciples say, “Send them away,” that each one may buy food, if he cannot from the cities, at least from the villages—places more ignoble.
Such things the disciples said, because, after the letter of the law had been abrogated and prophecies had ceased, they despaired of unexpected and new food being found for the multitudes. But see what Jesus answers to the disciples though He does not cry out and plainly say it: “You suppose that, if the great multitude go away from Me in need of food, they will find it in villages rather than with Me, and among bodies of men, not of citizens but of villagers, rather than by abiding with Me.
But I declare unto you, that in regard to that of which you suppose they are in need they are not in need, for they have no need to go away; but in regard to that of which you think they have no need— that is, of Me— as if I could not feed them, of this contrary to your expectation they have need. Since, then, I have trained you, and made you fit to give rational food to them who are in need of it, give ye to the crowds who have followed Me to eat; for you have the power, which you have received from Me, of giving the multitudes to eat; and if you had attended to this, you would have understood that I am far more able to feed them, and you would not have said, 'Send the multitudes away that they may go and buy food for themselves.'”
Source: Commentary on the Gospel of Matthew (New Advent)